.TH std::piecewise_constant_distribution 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::piecewise_constant_distribution \- std::piecewise_constant_distribution

.SH Synopsis
   Defined in header <random>
   template< class RealType = double >     \fI(since C++11)\fP
   class piecewise_constant_distribution;

   std::piecewise_constant_distribution produces random floating-point numbers, which
   are uniformly distributed within each of the several subintervals [b
   i, b
   i+1), each with its own weight w
   i. The set of interval boundaries and the set of weights are the parameters of this
   distribution.

   The probability density for any b
   i ≤ x <b
   i+1 is

   w
   i
   S (b
   i+1 - b
   i)

   , where S is the sum of all weights.

   std::piecewise_constant_distribution satisfies all requirements of
   RandomNumberDistribution.

.SH Template parameters

   RealType - The result type generated by the generator. The effect is undefined if
              this is not one of float, double, or long double.

.SH Member types

   Member type         Definition
   result_type \fI(C++11)\fP RealType
   param_type \fI(C++11)\fP  the type of the parameter set, see RandomNumberDistribution.

.SH Member functions

   constructor   constructs new distribution
   \fI(C++11)\fP       \fI(public member function)\fP
   reset         resets the internal state of the distribution
   \fI(C++11)\fP       \fI(public member function)\fP
.SH Generation
   operator()    generates the next random number in the distribution
   \fI(C++11)\fP       \fI(public member function)\fP
.SH Characteristics
   intervals     returns the distribution parameters
   densities     \fI(public member function)\fP
   param         gets or sets the distribution parameter object
   \fI(C++11)\fP       \fI(public member function)\fP
   min           returns the minimum potentially generated value
   \fI(C++11)\fP       \fI(public member function)\fP
   max           returns the maximum potentially generated value
   \fI(C++11)\fP       \fI(public member function)\fP

.SH Non-member functions

   operator==
   operator!=                compares two distribution objects
   \fI(C++11)\fP                   \fI(function)\fP
   \fI(C++11)\fP(removed in C++20)
   operator<<                performs stream input and output on pseudo-random number
   operator>>                distribution
   \fI(C++11)\fP                   \fI(function template)\fP

.SH Example


// Run this code

 #include <iostream>
 #include <map>
 #include <random>
 #include <string>

 int main()
 {
     std::random_device rd;
     std::mt19937 gen(rd());
     // 50% of the time, generate a random number between 0 and 1
     // 50% of the time, generate a random number between 10 and 15
     std::vector<double> i {0, 1, 10, 15};
     std::vector<double> w {1, 0, 1};
     std::piecewise_constant_distribution<> d(i.begin(), i.end(), w.begin());

     std::map<int, int> hist;
     for (int n {}; n < 1e4; ++n)
         ++hist[d(gen)];

     for (std::cout << std::hex << std::uppercase; auto [x, y] : hist)
         std::cout << x << ' ' << std::string(y / 100, '*') << '\\n';
 }

.SH Possible output:

 0 **************************************************
 A **********
 B *********
 C *********
 D **********
 E *********

.SH References

     * C++23 standard (ISO/IEC 14882:2023):

     * 28.5.9.6.2 Class template piecewise_constant_distribution
       [rand.dist.samp.pconst] (p: 1421-1422)
     * C++20 standard (ISO/IEC 14882:2020):

     * 29.6.9.6.2 Class template piecewise_constant_distribution
       [rand.dist.samp.pconst] (p: 1207-1208)
     * C++17 standard (ISO/IEC 14882:2017):

     * 29.6.8.6.2 Class template piecewise_constant_distribution
       [rand.dist.samp.pconst] (p: 1098-1100)
     * C++14 standard (ISO/IEC 14882:2014):

     * 26.5.8.6.2 Class template piecewise_constant_distribution
       [rand.dist.samp.pconst] (p: 962-964)
     * C++11 standard (ISO/IEC 14882:2011):

     * 26.5.8.6.2 Class template piecewise_constant_distribution
       [rand.dist.samp.pconst] (p: 955-957)
